COM Interop Presentation comments

&Agenda

=========================

•What is COM

•Why use COM

•C++ COM

•C# COM

•C++ Console calls C++ COM

•C# calls unmanaged C++

•Managed C++ calls C#

•Import C Plus Plus Dll in .NET

•Mapping type between C++ and C#

•Compiling COM

What is COM

ATL project

COM project

------ATLClass.h------

int

GetSelf(int x);

------ATLClass.cpp------

ATLClass::GetSelf(int x)

{

return x;

}

------CATLSimple.h------

GetSelf(int x)

STDMETHOD(GetSelf)(LONG x, LONG* y);

------CATLSimple.cpp------

STDMETHODIMP CATLSimple::GetSelf(LONG x, LONG* y)

// TODO: Add your implementation code here

*y=x;

return

S_OK;

------.c in COMPS project------

COM_i.c

COM_p.c

unmanaged: C++ console call C++ dll

#include "D:/COM/COM/COM_i.c"

#include "D:/COM/COM/COM_i.h"

int _tmain(int argc, _TCHAR* argv[])

IATLSimple * isobj=NULL;

HRESULT hr=CoInitialize(NULL);

if(SUCCEEDED(hr)){

hr=CoCreateInstance(CLSID_ATLSimple,

NULL,

CLSCTX_INPROC_SERVER,

IID_IATLSimple,

(void **)&isobj);

if(SUCCEEDED(hr))

long l;

isobj->GetSelf(1, &l);

cout<<l<<endl;

isobj->Release();

else

cout<<"Failed."<<endl;

CoUninitialize();

int i;

cin>>i;

return 0;

C# dll project

namespace CSharpClassLibrary

public class CSharpClass

public int GetSelf(int x) { return x; }

C# console project

namespace CSharpConsole

class Program

[DllImport("COM", EntryPoint = "GetSelf")]

public static extern int GetSelf(int x);

static void Main(string[] args)

Console.WriteLine(GetSelf(1));

Console.Read();

Managed: C++ calls C#

#include "stdafx.h"

using namespace System;

using namespace CSharpClassLibrary;

int main(array<System::String ^> ^args)

CSharpClass ^csc=gcnew CSharpClass();

Console::WriteLine(csc->GetSelf(1));

Console::WriteLine(L"Hello World");

Console::Read();

Unmanaged C++

extern "C" _declspec(dllexport) int GetSelf(int x){return x;}

•Component Object Model

•OO

•VB, C++,J++,C#...

•ONE Interface, Multiple Implement

Why use COM?

 Clipboard Technology

àDDE

àOLE1.0

àOLE2.0 (COM)

àDCOM

àActiveX

Advantages: CBD, Code Reusability, OOP, Communicate each, Network.

What is metadata 

Metadata stored information:

•Description of program set

•Flag(name, version, area, public key)

•Exported type

•Other program which this program set depends on.

•Running needed security permission

•Description of type

•Name, visibility, base, interface of implementation

•Member(method, column, property, event, nested type)

•Property

•Decorated type and members of other descriptive elements

Import C Plus Plus Dll in .NET

  Load Dynamically

•[DllImport("kernel32.dll", EntryPoint = "LoadLibrary")]

       public static extern int LoadLibrary(

           [MarshalAs(UnmanagedType.LPStr)] string lpLibFileName);

•[DllImport("kernel32.dll", EntryPoint = "GetProcAddress")]

       public static extern IntPtr GetProcAddress(int hModule,

           [MarshalAs(UnmanagedType.LPStr)] string lpProcName);

•[DllImport("kernel32.dll", EntryPoint = "FreeLibrary")]

       public static extern bool FreeLibrary(int hModule);

// function pointer

delegate int Add(int a, int b);

//1. Dynamically load C++ Dll

int hModule = LoadLibrary(AppDomain.CurrentDomain.BaseDirectory + @"CppInterop.dll");

if (hModule == 0) return;

//2. Read function pointer

IntPtr intPtr = GetProcAddress(hModule, "Add");

//3. Encapsulate function pointer to delegate

Add addFunction = (Add)Marshal.GetDelegateForFunctionPointer(intPtr, typeof(Add));

 • Load Statically

•[DllImport("CppInterop", EntryPoint = "ReturnBool", ExactSpelling = false, CallingConvention = CallingConvention.Cdecl)]

•        public static extern bool ReturnBool(bool str);